Since Feb. 18, when the state Department of Environmental Protection released natural gas production data for the second half of 2013, the department changed it at least eight times.

A disclaimer on the department's oil and gas reporting website states, "All production data is posted as it was received" and "the producers and DEP endeavor to correct any errors discovered after the data was posted." Users who view production data on one day might be looking at different data the next.

Act 13, the Oil and Gas Act, requires operators to submit production and waste data twice a year. Since 2011, the DEP has retracted and resubmitted portions of production data 94 times, according to an internal document it shared with The Times-Tribune.

These changes include operators who drill in conventional sources of oil and gas and unconventional formations, such as the Marcellus Shale. Most retractions were resubmitted the same day, but a few took several weeks.

Because of these changes, the newspaper had several errors in a Feb. 19 article on gas production due to retractions to 2012 data. Production data from Chesapeake Appalachia LLC, the top-producing gas company in the state, was missing at the time of download.

With Chesapeake's data missing, the newspaper miscalculated production statewide and by county for 2012 and the percent change to 2013. According to the most recent data available, Pennsylvania produced 2.05 trillion cubic feet of gas in 2012.

From 2012 to 2013, production increased 26.5 percent for Bradford, 37.8 percent for Susquehanna and 53.4 percent for Wyoming. The Feb. 19 article reported much higher rates of increase.

At this point, internal documents and interviews with DEP staff are the only ways to tell how frequently the department corrects production data.

Unconventional well operators' deadlines to submit their data come twice a year, Feb. 15 and Aug. 15, said Lisa Kasianowitz, information specialist and south-central community relations coordinator. The weeks leading up to these deadlines are hectic for the two staff members who curate the online spreadsheets.

"They're just on the phone all day long," she said.

Over the phone, they guide well operators on how to properly submit their data and troubleshoot problems that come up with the website, she said.

Operators of unconventional Marcellus Shale wells, which tend to be national or international exploration and production companies, tend to be better at submitting their data than conventional operators with only a few wells, she said.

"Sometimes we have operators say, 'OK, I'm going to get my grandson on the computer to do this for me,'" she said.

She said DEP staff often catch egregious errors, such as a small backyard well listed as producing millions of cubic of gas feet per day. More subtle errors are harder to spot.

"This is a self-reporting system, so we rely on the operators to submit the correct data," she said.

As the DEP adapts to its role in regulating the booming industry, plans are underway to make more of the data it collects publicly available, Ms. Kasianowitz said.

"As the industry has evolved, so have we, and we understand that the public wants to view these documents and reports and data," she said. "We're working on the appropriate way to do so."

One step she mentioned was the new oil and gas mapping tool launched in December, available at www.depgis.state.pa.us/PaOilAndGasMapping.

Users can plot conventional and unconventional wells for natural gas, oil, coal bed methane, storage and waste disposal, to name a few categories. They can also layer these points over maps of well pads, access roads, public lands, exceptional-value streams and geologic layers.

She mentioned well maps and violation reports as examples of what could be added to the mapping tool but said no specific time frame has been set to do so.

"In the future, we're going to put all kinds of well documents on the website," she said. "It's just ensuring we have the appropriate bandwidth and the resources to do so."

The DEP should at minimum make a revision history document or file available to the public, said Carl Hagstrom, founder of MarcellusGas.org, an independent website based in Montrose. Mr. Hagstrom compiles DEP data and makes it available to subscribers.

"As it stands now, there is no practical way to be able to accurately tell if any of the current files available at the site have changed," Mr. Hagstrom wrote in an email.

The DEP's disclaimer raises questions about how accurate production data are for royalty owners, Mr. Hagstrom said.

"If the agency in charge of monitoring unconventional well activity in the state can't vouch for the production data it provides, then who are royalty recipients suppose to turn to when confirming/validating the production values used by the gas company to determine the royalty payments?" he asked.

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